#include<stdio.h>

void swap_1(int *m,int *n){
	int *t;
	t=m;
	m=n;
	n=t;
}
void swap_2(int *m,int *n){
	int t;
	t=*m;
	*m=*n;
	*n=t;
}
void swap_3(int m,int n){
	int t=m;
	m=n;
	n=t;
}
int main(){
	int a=1,b=2;
	printf("a=%d,b=%d\n",a,b);
	swap_1(&a,&b);//can't change the value of a and b
	printf("a=%d,b=%d\n",a,b);
	swap_2(&a,&b);//can change the value of a and b
	printf("a=%d,b=%d\n",a,b);
	return 0;
}
